The company handling the Women’s Tennis Association’s controversial genetic sex screening has identity questions of its own—and neither the company nor the WTA appears eager to answer them.
Phuel Sports Science, a Colorado-based firm behind a performance blood-testing service, was chosen by the WTA to perform a one-time SRY gene screening test to identify the biological sex of competing athletes. The test is mandatory under a new eligibility policy enacted by the professional tennis tour that broadly restricts player participation to biological females, the first known implementation of such a policy in a major women’s sports league.
Yet basic information about the company entrusted with carrying out this mission is difficult to come by. Phuel founder and long-time CEO Garret Rock downplayed his current involvement in the company this week and declined to provide information on its current leadership. Multiple phone and email messages left with Phuel went unanswered. And the WTA has been similarly tight-lipped, telling Sportico it “will not be commenting on the private screening process including matters related to service providers.”
Independent tennis journalist Ben Rothenberg was first to report in his newsletter, Bounces, that Phuel had been selected to conduct the screening.
Phuel is carrying out the WTA work under the name Screening Sports, whose website appears to have gone live on July 20. A privacy and security policy linked on the site explicitly states the company is performing the screening “on behalf” of the tennis circuit. It describes the collection and handling of athlete data, the availability of genetic counselors and the need for parental consent for athletes under 18 years old.
It is unclear which laboratories will be responsible for processing the WTA players’ samples. Screening Sports’ website does not identify any specific laboratory partners. Phuel Sports Science has previously partnered with third-party labs such as Genova, Quest, LabCorp, OmegaQuant and Access Medical Labs.
The WTA’s sex-testing project comes amid an intensifying debate over how women’s sports determine eligibility for their competitions with respect to transgender athletes or those with differences in sex development. The discourse has spanned from high school sports to international competitions and pro leagues like the WNBA, where a pair of male former NBA players are currently claiming to identify as women to pressure a more definitive policy. Comments from athletes about the gene screening, including those made by tennis stars Coco Gauff and Aryna Sabalenka, are being closely scrutinized by fans on both sides of the dispute.
Limited transparency
Until now, Phuel’s principal consumer-facing business has been Athlete Blood Test, which, according to its website, offers a suite of blood-testing services to individuals, teams and organizations. With packages ranging from $129 to $1,049, Athlete Blood Test promises to identify “the most important biomarkers for athletic performance” and turn those findings into “actionable recommendations.”
The company says it works with dozens of major professional sports franchises, including the NFL’s Kansas City Chiefs and San Francisco 49ers, the NWSL’s Houston Dash and MLV’s Dallas Pulse. (Spokespeople for those teams did not respond to emails seeking comment.)
Phuel, however, makes it anything but transparent when it comes to who oversees its business. Neither Screening Sports nor Athlete Blood Test’s websites identify any executives, owners or other individuals behind their parent company, which has now been thrust into the highly sensitive role of managing the tests that will determine the eligibility of the world’s top female tennis players.
An “About” page on Athlete Blood Test’s site that previously detailed its leadership now leads to a dead link. As of last year, the page named Rock as CEO; Scott Evans as its chief revenue officer; Ofer Barniv as its head of day-to-day operations; Jordan Jones as web developer. Sports nutritionist Dr. Anna Seeward and Jacy Rock, Garret’s wife, were also included.
Evans and Barniv both indicate on LinkedIn that they currently work for Athlete Blood Test. Reached by cell phone, Barniv, a Minnesota-based certified physician assistant, declined to comment or provide information. Evans did not respond to a LinkedIn message.
Garret Rock, a chiropractor and self-described sports scientist, currently serves as co-CEO of Arete Healthcare, a network of providers offering coordinated care for muscle, joint and pain conditions. On state corporate filings, Arete Healthcare lists its principal address at a small shared office building in Golden, Colo. Screening Sports’ website lists the same address for Phuel—including the same suite: No. 35.
Ironman roots
When reached by text message last week, Rock suggested he has long had only a small, passive involvement in the company.
“I wish I could help you,” Rock said. “I own only a very small share and do not participate in operations. I am not in a position to be able to speak on behalf of the company or shareholders.”
In a 2022 podcast interview, Rock traced Phuel’s “origin story” back to 2007, when he was working at a medical clinic that served a number of elite and professional athletes. Rock said the work began with a study of blood results from 10 Ironman athletes.
“From there it really took off,” Rock said on the podcast. “We have had hundreds and hundreds of athletes that tested over the next few years, and from there it became driven by curiosity. We started to get answers to some of our initial questions of what is OK or what is not OK and then we started to seek findings that made us super curious.”
Phuel, originally called 51 Sports Science, was organized with the Colorado Secretary of State in 2015. Garret Rock was listed as the company’s registered agent for years. In 2024, Jacy Rock replaced him in that role. The company subsequently has used an anonymous commercial registered-agent service, further occluding its ownership.
By 2017, Garret Rock said in the podcast interview, he and his collaborators had accumulated enough data to conclude that the service could have a broader market beyond elite athletes.
“Here we are today,” Rock said, referring to 2022, when he conducted the podcast interview. “We test thousands of consumers, we work in pretty much every major sporting market with teams, individuals, national teams, professional teams in most major sports. We have a pretty big footprint and a really great database.”
IOC’s lead
The new WTA eligibility policy follows earlier guidance from the International Olympic Committee, which in March told international sports federations that it will start restricting participation in women’s events at the Olympics to biological females and that any woman seeking to compete in the Games will have to undergo SRY gene screening. The IOC directed sports federations and governing bodies to implement the policy as part of their eligibility criteria for the Olympics; in tennis, athletes earn qualification to the Games based in part on their WTA rankings.
The one-time SRY screening can be collected via saliva, a cheek swab or blood sample, according an FAQ on the Screen Sports platform. Those who test negative for the SRY gene are then determined to be “biological females.” Those who test positive for an SRY gene will not be permitted to compete in WTA tournaments unless further medical assessment establishes they have complete androgen insensitivity syndrome or other conditions which prevented the athlete from ever experiencing male puberty.
In a statement, the WTA said the updated eligibility policy is intended to clarify the standard for participation in tour events, and that “player screening will begin in 2026, following all appropriate confidentiality and data privacy safeguards and concurrent with a comprehensive player engagement program. The WTA recognizes that this is a sensitive and complex issue and is committed to treating all players with dignity and implementing the policy in a respectful and thoughtful way.”
Jessica Pegula, currently ranked No. 3 on the WTA Tour, told reporters at the Canadian Open last week that she was told the gene screening would begin as soon as the Cincinnati Open, which started Thursday. Other WTA players, including Sabalenka and Gauff, each gave nuanced support for the implementation of the policy.
Both the IOC and the WTA emphasized the importance of privacy and safeguarding athlete testing data as important tenets of implementing the gene screening. In its policy, the IOC says sports bodies must respect all data protection and privacy laws in their jurisdictions, and they must be transparent with athletes about how their personal data will be processed.
The WTA, for its part, writes in its policy that “all cases arising under this policy, and in particular all player information provided to the WTA under this policy, and all results of screenings, examinations and assessments conducted under this policy, will be maintained in strict confidence at all times. All medical information and data relating to a player will be treated as sensitive personal information and the WTA will ensure that it is processed by the WTA as such in accordance with applicable data protection and privacy laws.”
On the data protection, Phuel’s policy statement says personal information may be shared with third parties that provide services on its behalf, including medical professionals who review screening results, laboratories, specimen couriers and secure data-hosting providers. It asserts that those parties are contractually restricted to using the information only to carry out those services and that Phuel does not use personal data for advertising or marketing purposes.